Photocoupler Signal Transmission Circuit for Pulse Width Integrity
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Solution Overview
Problem
Conventional signal transmission circuits using photocouplers in hazardous environments face challenges in maintaining signal pulse width integrity due to differing rise and fall delay times, leading to pulse width changes, which can be costly to address with high-speed photocouplers that also have low withstand voltage.
Innovation Solution
A signal transmission circuit configuration that includes an edge detection circuit, light emitting and receiving circuits, photocouplers, an edge demodulation circuit, and an initial value setting circuit to synchronize and demodulate signals, preventing pulse width changes without increasing costs by using existing photocouplers within safe voltage limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a high-speed photocoupler is used to prevent pulse width change, then signal transmission speed is improved, but cost increases and withstand voltage decreases
Solution Approach 1:
The patent applies preliminary action by detecting signal edges (rising and falling edges) before they pass through the photocoupler. The edge detection circuits generate edge detection signals that capture the timing information of the original signal edges, allowing the system to reconstruct the pulse width accurately without requiring the photocoupler itself to be high-speed. This preliminary detection and subsequent reconstruction prevents pulse width changes while using standard-speed, high-withstand-voltage photocouplers.
2Manufacturing precision
If a high-speed photocoupler is used to prevent pulse width change, then manufacturing precision is improved, but cost increases
Solution Approach 1:
The patent detects edges preliminarily using edge detection circuits that generate edge detection signals. These signals capture the precise timing of signal transitions before they enter the photocoupler. By reconstructing the pulse width based on these preliminary detected edges, the system achieves high manufacturing precision (accurate pulse width) without requiring expensive high-speed photocouplers, thus reducing overall cost.
Solution Approach 2:
The patent introduces edge detection circuits as intermediary components between the input signal and the photocoupler. These circuits generate edge detection signals that serve as intermediaries to carry timing information through the insulation barrier. This intermediary approach allows standard-speed photocouplers to achieve high precision pulse width transmission by relying on the intermediary edge detection signals rather than requiring the photocoupler itself to be high-speed.
3Reliability
If insulation circuit is used to electrically insulate circuits, then safety is improved, but pulse width distortion occurs
Solution Approach 1:
The patent uses edge detection circuits as intermediary components that generate edge detection signals to carry timing information across the insulation barrier. This intermediary approach allows standard-speed photocouplers to achieve high precision pulse width transmission by relying on the intermediary edge detection signals rather than requiring the photocoupler itself to be high-speed.
Solution Approach 2:
The patent employs feedback mechanisms where the edge detection signals from both sides of the insulation circuit are compared and used to reconstruct the original pulse width. The system monitors the transmitted edge detection signals and adjusts the reconstruction process to accurately recover the original pulse width, providing feedback control that compensates for any distortions introduced by the insulation circuit.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively maintains signal pulse width integrity across insulation circuits without the need for high-cost, high-speed photocouplers, ensuring reliable and cost-effective signal transmission while adhering to intrinsically safe explosion-proof standards.
Implementation Method 1
a light emitting circuit (22a), a photocoupler (23a), and a light receiving circuit (24a)
Implementation Method 2
an insulation circuit such as a photocoupler and a transformer is disposed in a signal transmission circuit
Data Source
Figure 1
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Figure 4
AI summary
A signal transmission circuit includes a first photocoupler to which a transmission signal is input, an edge detection circuit which is disposed in a primary side of the first photocoupler, the edge detection circuit being configured to detect a rising edge and a falling edge of the transmission signal, and an edge demodulation circuit which is disposed in a secondary side of the first photocoupler, the demodulation circuit being configured to demodulate the transmission signal by using only one of the rising edge and the falling edge of an edge detection signal output from the edge detection circuit via the first photocoupler.